Abstract

This paper further investigated a previous study that discovered a strain of Bacillus cereus with a flocculation effect. Based on the initial medium, single-factor experiments were carried out to optimise the carbon and nitrogen sources and their concentrations. Inorganic salts with differing concentrations were successively tested through single-factor, orthogonal, and composite experiments, from which an optimal medium recipe was determined with the highest flocculation activity. Next, the flocculation activity and yield of the bioflocculant were compared between the optimal medium and the initial medium. The results showed that 40g/L mannitol was the optimal carbon source, and 4g/L peptone was the optimal nitrogen source, while 0.75g/L K2HPO4 was the highest amongst the inorganic salts. Considering the carbon sources, nitrogen sources, and inorganic salts, the optimal medium with the highest flocculation activity was 40g/L mannitol, 4g/L peptone, and 0.75g/L K2HPO4. It was found that the optimal medium increased the yield of the bioflocculant produced by Bacillus cereus by 189.70% and the flocculation activity by 58.87%, which was a significant improvement. These experimental results are of great importance in increasing the efficiency of wastewater treatment and reducing the cost of bioflocculant.